1. Field of the Invention
This invention relates to the treatment of vulnerable atherosclerosis and more particularly to an arrangement for the aspiration of a lipid pool within a coronary artery.
2. Prior Art
Atherosclerosis is the leading cause of coronary artery disease which may otherwise be called heart disease, which is the leading killer of men and women in the world today. It is characterized by deposits of fat, fibrin, cellular debris and calcium on the inside of arterial walls. The early stages of athersclorotic development is believed to occur as damage to the endothelial cells and tunica intima of the vessel wall. Once this damage has begun, the endothelial cells proliferate and attract a build-up of lipid substances. When these coronary arteries become blocked, symptoms ranging from angina to heart attacks, may occur. In a percentage of these cases, the coronary arteries may be unblocked through a non-invasive technique such as balloon angioplasty. Some five hundred to six hundred thousand angioplasties are performed each year within the United States. Where balloon angioplasty may not be appropriate, a bypass of the occluded or blocked vessel may be necessary. Identifying an opening such occlusions is known to give relief to the symtoms of angina, but it is also known that they do little to prolong life expectancy. The real killer in this coronary artery disease is often sudden blockages that are caused not by the slow accumulation of plaque that gradually block off the arteries, but by a sudden thrombosis (clotting) of the arteries caused by what are now referred to as xe2x80x9cvulnerable plaquexe2x80x9d.
Vulnerable plaques are defined as plaques prone, in the presence of an appropriate trigger, to events such as ulceration rupture, erosion or thrombus that can lead to an acute syndrome. Those events are believed to share three common characteristics, a large lipid pool, a thin fibrous cap and macrophage infiltration.
Current methods of diagnosing arterial disease, using such as stress tests as angiograms, are inadequate at detecting these xe2x80x9cvulnerable plaquesxe2x80x9d. Therefore, in most instances, this potentially lethal condition often goes untreated.
It is an object of the present invention, to provide treatment options for this particular condition.
It is a further object of the present invention to provide a plaque treatment utilizing an improved catheter apparatus to minimize the accumulation and potential danger of lipids within an artery.
The present invention relates to an aspiration/treatment catheter for the aspiration of a lipid pool within a coronary artery. The aspiration catheter comprises an elongated, flexible, polymeric shaft arranged to be pushed within a coronary artery. The aspiration catheter is hollow and enclosively supports an elongated needle. The needle is somewhat flexible, and functions as a guidewire to permit the advancement of the needle and catheter shaft to the situs of a lipid pool within a coronary artery.
The needle is flexible and steerable from the proximal end thereof, which proximal end extends outwardly from the proximal end of the aspiration catheter. The needle has a plurality of lumens therein. The first lumen is arranged to provide a suction at the distalmost tip of the needle, to a controllable vacuum source arranged in communication with the suction lumen at the proximal end of the needle. A second lumen is arranged within the steerable needle to function as a delivery conduit. The delivery conduit is arranged to bring a fluid or gas to the situs of the lipid pool, to permit the treatment of that lipid pool with a medicament or fluid agent.
A third lumen may be arranged within the steerable needle, which third lumen is arranged to contain an optic fiber. The optic fiber extends from the distal end of that steerable needle, within that needle, and proximally from the proximal and of the needle, to a monitor or eye piece, to be viewed by the operating physician. This permits the attending physician to steer the needle as necessary, and to apply medicaments and suction as needed.
In one preferred embodiment of the present invention, the steerable needle is movable longitudinally with respect to the catheter shaft. The steerable needle is preferably also movable rotationally with respect to that catheter shaft. The catheter shaft itself of course is advancable within the artery itself to the situs of the lipid pool.
In a further embodiment of the present invention, the aspiration catheter may have a position-indicating annular-band adjacent it""s distalmost end, to provide the attending physician with means for determining the location of the catheter by magnetic or electromagnetic means.
Thus, in operation of the present aspiration catheter, upon insertion of that catheter within a coronary artery, and location of a lipid pool covered by a fibrous cap, as evidenced by the optical determination thereof, or other sensing means, the needle is steered and advanced so as to penetrate the fibrous cap and suction the lipid material from its pool beneath the fibrous cap and adjacent the artery wall. A treating agent may be injected within the fibrous cap to facilitate removal of the lipid therefrom or to promote healing of the artery wall once the aspiration catheter and steerable needle have been removed therefrom. The fluid introduced into the lipid pool may be a pharmaceutical agent to render the lipid non-thrombogenic or to facilitate its solidification.
The present invention thus comprises a vulnerable plaque treatment catheter arrangement for the treatment of a lipid pool at a site of vulnerable plaque within an artery. The catheter arrangement comprises an elongated, hollow, flexible shaft having a proximal end and a distal end; an elongated, flexible, lipid-enterable needle arranged within the shaft, the needle having at least one lumen therethrough in communication with a treatment source, to permit the rendering of the lipid pool into an innocuous entity. The needle is rotatable within the hollow shaft, to permit the catheter to be steered. The lumen in the needle may be connected to a vacuum source to permit the lipid pool to be suctioned through the needle by said vacuum source. The lumen in the needle may also be connected to a pressurized fluid source to permit the lipid pool to be treated by a liquid or gas medicament. The lumen in the needle is connected to an optical viewing apparatus by an optical fiber to permit the lipid pool to be monitored by an attendant. The needle may have a plurality of lumens therethrough, each in communication with a fluid pressure source and a suction source respectively to permit a lipid pool to be suctioned and medicated thereby. The sheath may have a position indicator band arranged adjacent its distal end to permit locating of the needle relative to a lipid pool.
The invention also includes a method of treating a vulnerable plaque in a coronary artery by the use of a vulnerable plaque treatment catheter arrangement comprising the steps of: arranging a movable hollow needle in an elongated flexible catheter sheath; extending a lumen through the needle, from a distal tip thereof, to a treatment source proximal of the catheter sheath; pushing the catheter into an artery to be treated, so the distal end of the needle reaches a lipid pool in the artery; piercing a fibrous cap of the lipid pool by the tip of the needle; and actuating the treatment source to as to effect treatment of the lipid pool by the catheter arrangement. The method may include the steps of: providing a vacuum at the treatment source so as to provide a suction at the distal tip of the needle in the lipid pool to draw the lipid therefrom; providing a fluid pressure at the treatment source so as to provide a fluid to be introduced into the lipid pool in the artery; arranging an optical fiber through the lumen so as to permit the lipid pool to be monitored visually; steering the catheter sheath into the artery by articulation of the needle with respect to the sheath; suctioning the lipid pool by a vacuum source at the proximal end of the lumen; and introducing a treatment fluid into the lipid pool from a pressurized treatment fluid source through a second lumen extending through the needle. The method includes the steps of: viewing the lipid pool through an optical fiber arranged through a third lumen in the needle, the fiber having a proximal end in communication with a viewing monitor; wherein the fluid introduced into the lipid pool renders the lipid pool inert or renders the lipid pool into a non-thrombogenic semisolid material.
By such treatment, vulnerable plaques, heretofore defined as plaques which are prone, in the presence of an appropriate trigger, to ulceration, rupture, erosion, or thrombus that can lead to an acute syndrome, may be rendered innocuous.